1. Field of Invention
The present invention is directed to voice coil-actuated audio speakers, and more particularly to voice coil-actuated audio speakers having removable voice coils.
2. Discussion of Related Art
Many conventional audio speakers (also referred to herein simply as speakers) include diaphragms actuated by voice coils. For example, low frequency sound transducers (i.e. woofers) are typically comprised of such voice coil-actuated diaphragms. FIG. 1 is a cross-sectional side view of a conventional audio speaker 100 having a diaphragm 110 actuatable using a voice coil 122. Voice coil 122 comprises a wire which is wrapped about a substrate 124. The voice coil and substrate comprise a voice coil assembly 120.
Audio speaker 100 includes a voice coil drive system having an impedance rating. The drive system is comprised of an amplifier 113, and leads 130 to provide a current signal from the amplifier to voice coil 122. Voice coil 122 is maintained in a magnetic field provided by a magnet 140 and a pole 150, such that voice coil 122 and diaphragm 110 are actuated in response to the current signal. Actuation of diaphragm 110 produces an audio output. Voice coil 122 has an impedance suitable for use with the drive system.
A spider 160 (also commonly referred to as a suspension) operates to return diaphragm 110 to its initial position after and during actuation, and a frame 170 supports diaphragm 110. Frame 170 is connected to diaphragm 110 using a surround 180. A dust cap 190 is provided to protect voice coil 122.
Assembly of a conventional speaker system, such as speaker system 100, typically requires the performance of accurate assembly steps, many of which require special tools to complete. FIG. 2 is a cross-sectional side view of a partially assembled speaker system 100′ (with dust cap 190 shown in FIG. 1 removed). During assembly, a gap alignment device 210 is positioned to accurately maintain a gap g.sub.1 between pole 150 and voice coil assembly 120 while diaphragm 110 is attached to voice coil assembly 120 (at location 112), surround 180 is attached to frame 170 (at location 172), and spider 160 is attached to frame 170 (at location 162) and to diaphragm 110 (or voice coil assembly 120).
Each of the attachments is made using a permanent adhesive, such as an epoxy, to ensure that each attachment will remain secure during the lifetime of the audio speaker. After the adhesive cures, gap alignment device 210 is removed and dust cap 190 (illustrated in FIG. 1) is secured in place. In the resulting structure, the voice coil assembly 120 is supported by frame 170 in a manner such that the voice coil assembly 120 is centered about pole 150 (i.e., gap g.sub.1 is uniform about pole 150). Accordingly, during subsequent operation of the speaker system 100′ (i.e., during actuation of voice coil assembly 120 and diaphragm 110) voice coil assembly 120 moves without mechanical interference from pole 150.
An additional concern when assembling speaker system 100′ is providing an appropriate electrical connection between amplifier 113 and voice coil 122 so that the voice coil will be properly actuated. For example, the electrical connection must have an accurate impedance. Typically, to achieve an accurate impedance, leads 130 must be made of an appropriate material, have accurate lengths, and must be precisely soldered to the ends of voice coil 122.
In typical field use, damage to a voice coil is a common source of failure of voice coil-actuated speaker systems, such as audio speaker system 100 in FIG. 1. Voice coil damage may be acute (i.e., resulting from a single occurrence of excessive current), may be cumulative (i.e., resulting from excessive drive current over a lifetime), or some combination of both.
Despite the fact that voice coil damage is a common source of failure, there has been no convenient way to replace a voice coil 122 (or voice coil assembly 120). Replacement has been complicated by the need to remove one or more of the permanently-mounted components of a speaker, any or all of which may be damaged during the process, and the need to re-assemble the audio speaker (having a new voice coil) using the accurate assembly steps and specialized tools as described above. Because of these complications, repair of an audio speaker having a damaged voice coil typically requires taking the speaker system to a speaker repair shop or otherwise obtaining the services of a technician having any necessary tools and know-how.
Further, in many instances, even the process of getting a damaged speaker to a repair shop is an inconvenience. For example, many conventional systems are mounted in fixtures (e.g., a wall or ceiling of a building, or a dashboard, rear deck, or door of a car) such that a damaged speaker system may need to be removed from the fixture before repair can occur. For the above reasons, repairing a speaker having a damaged voice coil may require significant effort, down-time, and/or expense.